On Tue, 17 Jul 2012, James Bottomley wrote:
> On Tue, 2012-07-17 at 12:51 -0700, Linus Torvalds wrote:
> > Wrong people cc'd, it looks like.
> >
> > Guys, commit a7a20d103994 ("sd: limit the scope of the async probe
> > domain") is causing boot problems. It's timing-dependent and
> > apparently sometimes works, which makes sense with that commit.
> >
> > However, it *should* have been fixed by commit 43a8d39d0137 ("fix
> > async probe regression"), but Artem seems to report the problem even
> > in -rc7.
> >
> > Comments?
>
> As far as I can tell, the fix should have worked. However, there are a
> lot of assumptions in the async stuff that end up not being true in the
> presence of separate async domains. We should be fixing it all here:
>
> http://git.kernel.org/?p=linux/kernel/git/jejb/scsi.git;a=shortlog;h=refs/heads/async
Those commits haven't been merged into 3.5-rc7, right? So Artem isn't
using them.
> I've got to say, I don't understand the bug report. all of those
> commits were about probing for devices. However, the screen shot
>
> https://bugzilla.kernel.org/attachment.cgi?id=75351
>
> shows the devices were found, it's the partition tables that weren't.
> For us to see the message about sda's capacity, we're already in the
> async code the commits were trying to synchronise with.
That's understandable, given that those commits aren't present in
Artem's kernel. Are they queued for -stable?
> However, there are some missing messages: there's no partition table
> print and no final
>
> sd_printk(KERN_NOTICE, sdkp, "Attached SCSI %sdisk\n",
> sdp->removable ? "removable " : "");
>
> So sd_probe_async() got stuck somewhere after the first
> sd_revalidata_disk().
No, it didn't get stuck. The problem is that the scsi_wait_scan module
didn't wait for the async scanning to finish.
And the reason for that is one you're already familiar with:
CONFIG_SCSI_MOD=y.
Artem, if you change all your SCSI drivers to be modular rather than
built-in, that ought to fix the problem. Alternatively, you can simply
continue to use the "rootwait" option.
Alan Stern
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